GitHub Packages

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Prerequisites

• Install Docker Desktop
• .NET 6

Loose Agenda

• Build a container image
• Store our built container image in GitHub Packages

Step by Step

Setup Playground

Create a new directory for this exercise and navigate a terminal instance to the new directory.

Create a Web API

From the terminal instance run dotnet new webapi -n non-zero-packages -o .

Open Program.cs

• Remove app.UseHttpsRedirection(); from line 19.
• Remove if (app.Environment.IsDevelopment()) surrounding to enable swagger on all builds.

Your Program.cs should now look something like:

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

// Configure the HTTP request pipeline.
app.UseSwagger();
app.UseSwaggerUI();

app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

app.Run();

This will create a .NET WebAPI in the current directory. You can run dotnet build to verify it produced a viable application.

Add a New Endpoint

Let’s create a new endpoint that prints out a configuration value.

Open Controllers\WeatherForecastController.cs and add IConfiguration to the injected dependencies.

    private readonly IConfiguration _configuration;

    public WeatherForecastController(ILogger<WeatherForecastController> logger, IConfiguration configuration)
    {
        _logger = logger;
        _configuration = configuration;
    }

Add a new GET endpoint which returns the value of the NON_ZERO_VALUE configuration.

    [HttpGet("configuration")]
    public string NonZeroConfiguration()
    {
        return _configuration.GetValue<string>("NON_ZERO_VALUE");
    }

Add a Dockerfile

In the root directory, add a new file named Dockerfile.

Add the following content to the Dockerfile

FROM mcr.microsoft.com/dotnet/sdk:6.0 AS build-env
WORKDIR /app

COPY *.csproj ./
RUN dotnet restore

COPY . ./
RUN dotnet publish -c Release -o out

FROM mcr.microsoft.com/dotnet/aspnet:6.0.0 as final
WORKDIR /app
COPY --from=build-env /app/out .

EXPOSE 80
ENTRYPOINT ["dotnet", "non-zero-packages.dll"]

Build and Run the Image

From the terminal in the root directory, run docker build -t webapi .

Now let’s run the produced image while setting our NON_ZERO_VALUE configuration.

docker run -it -e NON_ZERO_VALUE=day -p 803:80 webapi

Open a browser to http://localhost:803/swagger.

Call the /WeatherForecast/configuration endpoint and note the response is our configured value day.

Push to GitHub Packages

For this step, you’ll need to generate a Personal Access Token (PAT) via the tokens page on GitHub. Generate a new token with the write:packages permission.

NOTE - For the purpose of this exercise I’m going to store a PAT in a session variable $CR_PAT.

Log in to the GitHub Packages container registry ghcr.io by running echo $CR_PAT | docker login ghcr.io -u USERNAME --password-stdin

Tag the webapi image by running docker tag webapi ghcr.io/YOUR_GITHUB_USERNAME/non-zero-packages:latest

Push the image to GitHub Packages by running docker push ghcr.io/YOUR_GITHUB_USERNAME/non-zero-packages:latest

Navigate to GitHub and check out the Packages tab on the associated profile. You should see your image!

On the right of the image’s page you should see Package settings wherein you can change the visibility or delete your image.

Congratulations on a non-zero day!

Additional Resources

• GitHub Packages Documentation